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Question
A wire 5 m long is supported horizontally at a height of 15 m along an east-west direction. When it is about to hit the ground, calculate the average e.m.f. induced in it. (g = 10 m/s2)
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Solution
Given:
h = 15 m, l = 5 m, g = 10 m/s2, e = ?
Formula:
e = Blv
The magnetic flux density (B) due to the earth's magnetic field is about 3.6 × 10-5 T.
Assuming that the wire is falling vertically under the influence of gravity, we can use the free fall equation to find the velocity (v).
∴ v = `sqrt(2gh) = sqrt(2 xx 10 xx 15)` = 17.32 m/s
Now, e = Blv = 3.6 × 10-5 × 5 × 17.32
∴ e = 3.1176 × 10-3 volts
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